It is generally known that in fully soild material insulated high voltage switching and distribution equipment, the bus bars and the equipment of the main current path which are provided with an insulating cover from a solid insulating material including outer shield from, for example, a grounded conducting layer, are coupled and interconnected over separable connecting points.
As it is known from WP52449 a necessary insulating capability of a fully solid material insulated connecting point is achieved in that, an air gap which is created between the fully solid material insulated bus bars or equipment, becomes electrically sealed with an insulating material having higher electrical stability by being spanned by an elastic insulating material.
Furthermore, it is known from WP82981, a radially mountable conductor train which can be arranged between two fixed points and having a solid material insulation, more specifically, a bus bar for high voltage switching equipment, which comprises the combination of a separable elastic connecting point, a separable rigid connecting point and a rigid solid material insulated conductor arranged between the two connecting points. The conductor ends are formed as lugs and individually are surrounded by axially displacable contactor segments which are assembled each into a hollow cylinder, wherein the necessary contactor pressure is produced by an insulating material ring which is spanned or compressed between the insulation of the conductor ends.
Furthermore, there is known, a connecting point for solid material insulated rigid conductors, especially for bus bars, from WP60081, in which, on both sides, in the conductor ends which are provided with drilled holes on their front sides, pressed balls under spring action are held, which bring about the electrical connection of the current conducting conductor over a slotted contact sleeve. Between the solid material insulation of the conductors there is an elastic insulating ring arranged, which is held by two limit rings. The connecting point is spanned by means of annular springs, metallic threaded rings and by a metallic threaded sleeve arranged on the solid material insulation. From the present prior art technique a substantial disadvantage comes to light in that the coupling of fully solid material insulated current conductors and component joints which are capable of carrying high currents cannot be made or checked before the air gaps are sealed off by spanning, in order to attain the necessary electrical insulating capacity.
Inasmuch as in the known solutions, after the sealing of the air gap the access to the current conductor ends is not possible and during the sealing procedure the access with tools to the current conductor ends is very limited as far as space is concerned, in a practical application, the connecting methods which are especially suited for the attainment of a low contact transition resistance, such as bolt connection, pressing, soldering, welding or coupling by clamping pieces, will be eliminated.
Therefore, inescapably one must fall back on arrangements which are not beneficial for the current transition, such as on contact lamellae pressed by spring force or on segments. Under these conditions it becomes insignificant whether the contact force is produced by spanned elastic synthetic materials (WP82981) instead of by springs. For example, according to WP60081, the contact force is produced by the spanning or compression during the sealing of the gaps. Not only that the actually produced contact force and the spatial position of the connecting elements due to the inescapable tolerances of the individual components cannot be ascertained anymore, the danger is present that although the spanning will guarantee a sufficient insulating capability for the gap sealing, the contact forces for the current transition will not be produced to the required extent. Also during the heat effects influencing the fully solid insulated bus bars, the spanning and consequently the contact pressure will change in an extent beyond control. This disadvantage will not be eliminated even by the solution offered by the radially mountable solid material insulated conductor train according to WP82981, inasmuch as also here, the contact force of the lamellae will be produced first only by the compression of spanning of the gaps during sealing. A further disadvantage of the above-mentioned technical solution resides in that the connecting points can be mounted only with a pair of current conductor ends in the same axis, but not under an angle or by branching off.
The last mentioned disadvantage will be partially removed by the switching equipment known from DE-AS 1295052, disclosing a switching equipment for high operating voltage having fully insulated encapsulation of the bus bar components and branch conductors in each phase. In this switching equipment the bus bar components and the branching-off conductors which are encapsulated exclusively in solid insulating material are lead into a branching-off housing comprising an insulating synthetic material having a certain elasticity while electrical gaps are created, and in which housing the bus bar components are electrically coupled with each other and with the branch-off conductors by means of annular spring contacts arranged on a coupling element. For the distribution of the electric field in the elastic branching-off housing a elastic shield electrode is built into. The elastic branching-off housing serves especially the purpose to compensate the longitudinal expansion of the bus bars during heat effect.
In addition that such elastic branching-off housing is technologically extremely difficult to realize, such solution further has a disadvantage, that the current carrying coupling is created only after the sealing off of the gaps and, that the seating of the contact elements and their contact pressure which depends from the inescapable tolerance conditions and displacement, cannot be controlled anymore, in that the annular spring contacts can be used only which are not quite suitable for the transition of high currents and are relatively complex and, that in order to reduce the contact transition resistance by suitable coupling methods, such as by bolt connection, pressing, welding, such methods cannot be used. In addition, such connecting point cannot be varied in order to be useable for all kinds of branching-off conductors.
A further disadvantage resides in that the supervision and repair on the couplings is possible only after disassembling the entire bus bar and branching-off arrangement.